80mph is
stock - 3110 rpm
3.91 - 3350 rpm +240 rpm over stock
4.10 - 3520 rpm +410 rpm over stock +170 rpm over 3.91
wider tires (265/35 and 275/35) will add another 1.7-2.8% roughly +50 and +90 rpm.
Honestly 4.10 is not a huge change, the difference from 3.91 to 4.10 is a little more than half the difference from 3.62 to 3.91.
3.91 vs 4.10 is definitely a personal choice and will depend on the goal of your build. Most things in life are engineering trade-offs, tikamak brings up some great points
